This invention relates to a mining machine for underground mining operations, and more particularly to an improved drive arrangement wherein a chain extends along the mine face and is anchored at spaced-apart locations throughout its length to substantially reduce stretch of the chain which would otherwise occur as the machine propels itself along the chain.
Drum-type cutter-loader mining machines are known in the art for underground mining operation wherein the drum cutter-loader is movable along a face conveyor through the agency of a sprocket wheel which engages a round-link chain extending along the length of the mine face and by which the drum cutter-loader pulls itself therealong. As the mining machine advances along the mine face, the winch sprocket is located in a manner such that it displaces a short length of the chain from its normal extended position. The displaced length of the chain is usually confined between rollers which are disposed before and after the winch sprocket in relation to the length of the machine. The displaced length of chain is therefore generally bounded between these guide rollers. The leading roller retains the chain in its original position and the trailing roller returns the chain links passing from the winch sprocket back to their original or normal position. In relatively long mine faces, the winches must develop a relatively high torque that develops a relatively high tension in the chain which tension can be of the order of 20 Mp during the mine cutting operation. This magnitude of chain tension causes considerable stretching of chain and a stretch of up to 1 meter or more from its normal or free length underground which length is usually within the range of from 150 to 200 meters long. This chain stretch occurs even in instances where a heavy round-link chain is utilized. The chain stretch increases the noise produced by the drum cutter-loader. Moreover, in the event of abruptly changing loads on the chain, the stretch is responsible for severe impacting by the chain. This leads to oscillations of the heavily-loaded part of the chain and, hence, to a constant danger to the machine operator and other personnel in the mine.